Question

State the suffix in the name for each of the following: (a) \(\mathrm{Na}_{2} \mathrm{SO}_{3}\) (b) \(\mathrm{H}_{2} \mathrm{SO}_{3}(a q)\)

Short answer

(a) 'ite'; (b) 'ous'

Step-by-step solution

Identify the Anion in Na2SO3

In the compound \(\mathrm{Na}_{2} \mathrm{SO}_{3}\), sodium (Na) is the cation and sulfate (\(\mathrm{SO}_{3}\)) is the anion. The anion \(\mathrm{SO}_{3}^{2-}\) is known as sulfite. The suffix for sulfite in the IUPAC naming is 'ite.'

Determine the suffix for Na2SO3

Since the anion suffix is 'ite' for \(\mathrm{SO}_{3}^{2-}\) (sulfite), the suffix in the name of \(\mathrm{Na}_{2} \mathrm{SO}_{3}\) is 'ite.'

Identify the Anion in H2SO3(aq)

Here, the compound \(\mathrm{H}_{2} \mathrm{SO}_{3}\) is an aqueous solution of sulfurous acid. The anion formed once the acids donate hydrogen ions is sulfite (\(\mathrm{SO}_{3}^{2-}\)). The naming of acids depends on the anion suffix; 'sulfite' changes to 'ous' for acids.

Determine the suffix for H2SO3(aq)

With the anion being sulfite and its suffix 'ite,' when naming acids, the suffix 'ite' is replaced with 'ous.' Thus, \(\mathrm{H}_{2} \mathrm{SO}_{3}(aq)\) is named as sulfurous acid. The suffix 'ous' signifies the presence of the sulfite ion as the anion.

Key concepts

Anion Identification

Anions are negatively charged ions that form when an atom gains electrons. In chemical compounds, distinguishing between the cation (positively charged ion) and the anion is crucial for proper nomenclature.
To identify the anion in a compound, look at its chemical formula. For example, in \(\mathrm{Na}_2\mathrm{SO}_3\), the anion is \(\mathrm{SO}_3^{2-}\), which is known as sulfite. It pairs with the cation sodium \((\mathrm{Na}^+)\).
When working with acids like \(\mathrm{H}_2\mathrm{SO}_3(aq)\), the process is similar. After the hydrogen ions are donated by the acid, the remaining part, \(\mathrm{SO}_3^{2-}\), is identified as the anion. Recognizing the anion is the first step in determining how the compound will be named in accordance with IUPAC rules.

IUPAC Naming

The International Union of Pure and Applied Chemistry (IUPAC) system provides rules for naming chemical compounds to ensure uniform communication in the scientific community. Understanding these naming conventions is key for both writing and interpreting chemical formulas.
In the IUPAC naming of ionic compounds, the name of the cation is given first, followed by the name of the anion with the appropriate suffix.

• The suffix 'ide' is generally used for simple anions (e.g., chloride for \(\mathrm{Cl}^-\)).
• For oxyanions (anions containing oxygen), suffixes 'ite' and 'ate' are used based on the oxygen content. 'Ite' indicates one less oxygen than 'ate' (e.g., sulfite \(\mathrm{SO}_3^{2-}\) and sulfate \(\mathrm{SO}_4^{2-}\)).

Such conventions ensure clarity and reduce misunderstandings in scientific communication.

Acid Naming Conventions

Naming acids involves altering the suffix of the anion contained within the acid. This system indicates the presence and characteristics of the anion when the acid is in an aqueous solution.

• When the anion ends in 'ide,' the acid name starts with 'hydro-' and ends with '-ic.' For example, chloride (\(\mathrm{Cl}^-\)) becomes hydrochloric acid (\(\mathrm{HCl(aq)}\)).
• If the anion ends in 'ate,' the acid name ends in '-ic.' For example, sulfate (\(\mathrm{SO}_4^{2-}\)) transforms to sulfuric acid (\(\mathrm{H}_2\mathrm{SO}_4\)).
• When the anion ends in 'ite,' the acid name takes the suffix '-ous.' For example, sulfite (\(\mathrm{SO}_3^{2-}\)) results in sulfurous acid (\(\mathrm{H}_2\mathrm{SO}_3(aq)\)).

Fluency in these rules helps predict the structure and properties of acids from their names, as well as construct their chemical formulas from given nomenclature.